This invention relates to a pneumatic conveyor for empty, lightweight bottles of the kind incorporating a support flange at an area of their neck and which are propelled by air jets along supporting and displacing guides.
In the state of the art, different pneumatic conveyors of this kind are well-known, among which those disclosed in patents EP-0 070 931, EP-A-0 705 777, EP-A-0 790 200 and WO 90/10587. In each of them the conveyors disclosed show a general common configuration which comprises, at least, a supporting structure for, at least, two coplanar parallel tracks for supporting said flanges and apart from each other by a predetermined gap which defines a guide path of said bottles run; a plurality of blowing nozzles, distributed along each of said supporting tracks and located adjacent to them which provide air jets which propel the bottles; at least a pressurizable chamber communicated with said blowing nozzles; and at least an inlet for supplying compressed air to said chamber.
The conveyor disclosed in said patent WO 90/10587 stands out in that, with a general configuration as above disclosed, said air nozzles are arranged above and under a single pair of supporting tracks for the flange, therefore the air jets affect the area of the neck and upper part of the bottle neck. Said patent EP-A-0 705 777 discloses, on its hand, a conveyor likewise provided with a single pair of supporting tracks but, that, in addition to said blowing nozzles, which in this case are directed up to the upper part of the neck, the pressurizable chamber has passageways for air circulating and deflectors which distribute other air jets which impinge, in upwards and forwards direction on the part of the upper half of the bottle body.
These conveyors which have a single pair of supporting tracks, show the drawback that the stability of the bottles run is very sensitive to any unbalance or irregularity between the thrust power of the air jets which impinge on the areas located above and the areas located under the flange guiding said bottles, so that the bottles have a significant likelihood to rotate each other and to get clogged in the conveyor guide path.
Patent EP-0 070 931 shows a conveyor of above kind in which two pairs or tracks are present; one pair of lower support tracks and one pair of upper guiding tracks. In this example, however, the air jets impinge exclusively on an area of the bottle neck located above the flange. Therefore, the possible benefits arising from the advantage of having a double guiding track are lost because of the unbalance sustained by the areas of the bottles which receive the thrust of the air jets. Actually, as the thrust is exclusively carried out by the part located above the guiding area, that is to say, above the flange, the bottles tend to tilt forwards, so that the front part of said flange presses against the sliding surface of the lower supporting track and the rear part against the upper guiding track, the friction force negatively increasing contrary to the bottles running forwards which implies a significant loss of power which means an increase of the air, supply cost and the likelihood of irregularity in the carriage and even eventual obstructions.
It is to be noted that in this kind of equipment the clogged bottles means a serious drawback because to remove them the line has to be stopped and part of the pressurizable chamber and of the guides must be dismounted which means an unbearable stop of the whole bottle feeding line at a bottling section, which obliges to arrange backup auxiliary conveying lines.
Finally, said patent EP-A-0 790 200, of which this applicant is the proprietor, discloses a conveyor which incorporates a pair of lower supporting tracks and a pair of upper guiding tracks, and characterised in that the blowing nozzles are located at either side of the guide path formed by them so that the air jets impinge just on the bottle guiding area, that is to say, on the flange and neck areas immediately adjacent so that a very even bottle run is achieved because of an accurate guiding and a balanced thrust. The conveyor in addition comprises two of said pressurizable chambers, independently feeding the nozzles at either side of the guide path in order to allow that a third chamber is incorporated, in this case a suction chamber, in the space located immediately above said guide path for lightly and upwardly sucking the bottles favouring this way a diminution of the flange friction with the supporting track.
Although this arrangement at operating level evidenced to be fully effective and satisfactory, however it can be improved over all on the construction aspect. Actually, in this conveyor, as well as in the remaining conveyors considered, the pressurizable chamber or chambers feeding the blowing nozzles are made of a rigid material, generally metal sheet, which is expensive as a raw material, expensive to conform, namely if airtightness is required, because it implies cutting, folding and welding with some accurateness and that calls for bothersome mounting and dismounting and therefore, an also expensive general maintenance of the equipment.
Therefore, an object of this invention is to contribute with a pneumatic conveyor for empty lightweight bottles, comprising accurate guiding means, a balanced distribution of the thrust air jets and at least a pressurizable chamber and blowing nozzles cheap to construct and easy to mount and dismount which imply therefore low cost of production, mounting and maintenance.
Another object of this invention is to contribute with a conveyor of this kind which has in addition means allowing to quickly remove from the line of bottles eventually clogged, even without stopping the conveyor is required.
These objects are achieved in a pneumatic conveyor for empty lightweight bottles, according to this invention, contributing at least with a pressurizable chamber formed by means of an airtight removable wrapping, secured along the supporting structure of the conveyor by airtight, removable junction means so that a quick access is provided to the area for distributing air to the tracks for their cleaning, maintenance and eventual fitting and/or adjustment. Said removable wrapping is flexible, preferably made of canvas although it could also be any other laminar flexible and airtight material, as for example, plastic sheet, coated or impregnated paper, or even a thin metal sheet such as aluminium.
The conveyor according to this invention is suitable to incorporate just one of those wrappings, forming a single pressurizable chamber associated to the blowing nozzles arranged at either sides of the tracks, along all of them, in which case the area comprised between said tracks, within said chamber, is covered by a profile configuring a reversed channel to allow the passage of the bottle necks. This profile, on one hand, partly acts as supporting structure joining the tracks to each other and keeping the suitable distance for the guide path, and on the other hand, closing the pressurizable chamber at the area of said guide path.
In the event that it is considered of interest to have a free space available at the higher area of the guide path or even an access to said path from said area, as it is the case of the suction chamber disclosed at mentioned patent EP-A-0 790 200, of which this applicant is the proprietor, the conveyor according to the invention can incorporate two of said wrappings forming two side pressurizable chambers, each associated to the blowing nozzles arranged along one of the tracks. Here, the area comprised between said tracks is also covered at the top by a profile, although in this case said profile only acts as said partly supporting structure, so that, as it does not constitute a part of the chamber closing, it can be provided with opening having access to the guide path. In addition, as the two pressurizable chambers remain in a lateral position, the area located immediately above said profile remains clear.
The embodiment of said chamber or chambers in a flexible laminar material, such as for example, a tarpaulin, allows a significant diminution of the costs as well of production as of mounting and maintenance, because it is a cheap material, easy to work and with little requirements of conformation because it is easily adapted to possible unevenness of the conveyor design and it allows quick mounting and dismounting which carries a saving in maintenance because it allows an easy access to the area distributing the air to the blowing nozzles for their cleaning or repair and even an access located at a portion of said area by partly dismounting an edge of the wrapping.
In an example of preferred embodiment of the invention, said blowing nozzles are arranged between each of said two supporting tracks and each of other corresponding two parallel, coplanar tracks for higher guide of said flanges. Therefore, the air jets injected by the nozzles impinge just on the flange, which is guided as well by the lower part as by the higher part, and neck areas immediately adjacent, that is to say, on the guiding areas of the bottles, which confer to them a balanced thrust which carries a great forwards run evenness.
In order to cut down ever more the costs, the conveyor of the invention includes the assembly of blowing nozzles at either side of the guide path in two bodies, each sandwiched between each of said two supporting tracks and each of said two higher guiding tracks, the bodies of which are crossed by passageways communicated by one end with at least one of said pressurizable chambers and the other ends of which define said blowing nozzles.
Each of said bodies is obtained from cutting a large-sized plate formed by two superposed sheets, close to each other, joined by walls parallel to each other, which cooperate with said sheets for defining said passageways, which are configured such as cells open by the edges. Cutting said large-sized plate can be carried out obliquely to the walls, so that it forms with them a given angle, which can be selected depending on the working angle required for each application for the propelling air jets. Said large-sized plate is of plastic material and is obtained through extrusion, therefore the making of said bodies, including air passageways and blowing nozzles, results very simple and cheap.
In addition, by giving to said body a suitable height, its sandwiching between a lower supporting track and a higher guiding track provides a gap between the actual portions of said tracks suitable to the thickness of the flange of the bottle, with which no further adjustments are required, which facilitates mounting to a great extent, having a favourable repercussion on the costs of said mounting in addition to those of the further maintenance.
In order to provide the conveyor according to the invention with means allowing to easily withdraw any bottle eventually clogged in the line, in at least one of said sandwich composed, the higher guide track and the body are joined to the structure by rigid means, while the supporting track is joined to said structure by independent elastic means, so that any bottle which unintentionally is clogged within the guide path of said tracks could be immediately released forcing at hand said elastic joining means to take the supporting track apart.
The supporting structure in addition comprises two extensions, each joined by one side to one of said sandwiches composed of the tracks and the body of the nozzles and on the other hand to an edge of said pressurizable chamber, which is at least one, therefore said extensions also constitute part of said chamber closing. At least, one of said extensions is joined to at least one supporting element of the conveyor, such as a column or an overhanging fixed arm.
In addition, means have been provided for adjusting the passage of the air between said pressurizable chamber, which is at least one, and said blowing nozzles through the passageways of the body. Said means comprise obturating plates associated to said nozzle bodies which can be locked in a position selectable for partly obturing all the passageways or for totally and selectively obturating some of the passageways at regular intervals. On the other hand, said obturating plates can be moved and/or fixed to said hand selectable position, having access to them by previously dismounting said removable wrapping, they can be longitudinally guided and be moved and/or fixed to said selectable position by suitable driving means, such as an electric motor or a fluid dynamic cylinder.
Last, it has been foreseen that the conveyor according to the invention comprises several of said inlets of compressed air supply to the chamber, distributed along the conveyor depending on the length thereof, and that the equipment comprises its own blowing or compressing air means connected to said different inlets for supplying compressed air to the chamber.
Said means, which must provide a great air feed at a relatively low pressure, can be formed by a single blower or compressor capable to feed the whole line, with a feeding duct provided with a branch for each of the inlets of the chamber, or a plurality of small blowers or compressors connected each to one inlet for feeding a length of the chamber. However, it is obvious that the conveyor of the invention can also be fed from a compressed air plant already existing in an industrial premise in which it is integrated or pertaining to another machine to which it is associated.